SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc125452209b3778676f6860fd8261b1d859c201c4763785ad54d4ae1f691f31' 
  AND token = 'eiiPpURyDU7sa4QmMwJ+SOnOiSCcYCJ2cdaIAnWnyAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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