SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a81dd22513bda732f97e5943514119459e1d6e903376269f1484b7659bdcbc2' 
  AND token = 'Zs4gZ+pTFsNoTV5490hbyziEtXPrn5VSsjksQUmlkD4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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