SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '778a28d122f1b053aa1951f4915a115a7babb8936e359aa385a159caff802495' 
  AND token = '0Th2qJ8MwkTpRnirFWQXSSC0V33buv7Q0qQVeYlf+Eg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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