SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b296d33867f32108d308575810695bbd87fa12f45238574f2423857bbea1754e' 
  AND token = '6LVP3uRiSiN8wFKe4M1K7pTmeZ6nCQcBPubXpW6nh+A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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