SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '795552d9ec08a01c23a6928e42da8783a5216001483db499d71e0e06aee29644' 
  AND token = 'RKrtWkoG1ZmpQOOFSgLYMhQb78yDePvQfWGrASJ1bPA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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