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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50f5df408691af91a9669b7c5e351459423e26b1dd7b3a2ddf2e5c15b10d5c1f' 
  AND token = 'wkYwsA8mxrdBDeQtRq9ZiuSrZfArBvzBgp5s6kspCq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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