SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e257f60852df5007d60cac895f475421d752db36b937b70336a0aff3b1a9fa4' 
  AND token = '3Jcyiwum3yxwtJlcvjULp7hACLLNc/iHp0QdrR0xJVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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