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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '558a681ea71a8e4c5a1074934ad31d50fdd05e0e8d3248d9a10bfc34e2f9b2cb' 
  AND token = 'O/tz4Dz8PWTbVD74knATdqKSQJVjoPub8upQ1DmAPcI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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