SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b46b302913ed6c297b6c44729dffae11e8aae009fd1c604266771185f2a8445e' 
  AND token = 'tpujsC/LAWagUtpavyG4szE5mlYG4bh+zen7huOxWo8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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