SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad91886d900be2315e2cb3e1443a0871386570fab46deead210de96e777555a2' 
  AND token = 'Ap5JhMh80DO6shpFfZoza+tgj/SihizZrW26dLUuxM8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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