SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '231b442de4a33426b21c3e655b871195b72d0d964d240b7b73b52b2a735fd804' 
  AND token = 'KB7fmkXgyuJmKYam4xcMEJ3sbkFvnRHSeOPYO5wkqN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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