SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9af34fb2e2278648a0d723d8174541274ebddfc7db217b93e9fa5821297d5f8c' 
  AND token = 'l/QvQ1oj1vErUXRTI3ZclpHAgpV4Kz2Dojb5gg7PGSM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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