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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76c7d121d37e86774a6f86a83af006e6835771aa474ec282f684f7332e2ab807' 
  AND token = '6SPh2bfhN8zM+22AyvA0+NoO+xKCQxCfpQ58M1WBrDQ=' 
  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"
    }
  }
}