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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c419e8747494d6a5704bf66c83b400070c22a3d2f36e9d2c7b56e4b1c2ec6363' 
  AND token = '6uFt9d5P0Loeckvm+qInFukWuMaybamKs/4Putppfzo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}