SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b81be1c247f20deca3b5c65bf0a8405a38caf268f4ae3d6f58f667f04598aa9a' 
  AND token = 'uKxy0MMuZGUj8qZxfmcS4QHDPcsK85TaMOJrTyOeIlA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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