SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f97d3882289348529734b309996df1459b28f3c62bde8038856e49ad83875c53' 
  AND token = 'zNfm1oBxULFzWao8PiU+ZY+wF6ujdVKi0/nU7MsMfC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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