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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df8b91e6d3125b4545a447e2f48c6f2390320254bbb1f0e4d40a17a4ab8e4f91' 
  AND token = 'h0/sFFM8cNmftVlZjbf4g6btB6XVPZ9w5y74/fk18ZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}