SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '58e75b8ea95e21bff37848e76b4f09afb9e5ada9b120b526cf5a15f37f45f497' 
  AND token = 'S3IoovUKca2POafqlBMM1VbJBZH+zzr6EoTWRxEDkoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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