SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'de28c83035dba2bd0c5babd09c6c38fea489f169128599003fa88e9537569a9e' 
  AND token = 'FTTYX1GHYblCwLiriLcwwdaBwnDCyaFlI2W/MRfeC4E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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