SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '978d268aaa8356ea23abd174ffd8a01829d1ecc7f1d4ac3a8b2e0218750e2455' 
  AND token = 'FlqWRrilhbQK27t9mVrdzrlYOxJd0yzbFFWd719QWL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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