SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f6a9ecaa51528fa643658798121bff0734e018d1279a84532d55565ab1052f10' 
  AND token = '/DBLNszgQYNopUpDUHazgfRwwyx47+Bb9ucZOxVWRZ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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