SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd0a7236fbfb4c4abd939164b7c2fdf19086bb88404059eedb6dba3703f5c624' 
  AND token = 'NfEMIEoQ0JaRBWJ5gxAlHk6GgnEFezwgijarXByA8S4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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