SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f18522b58cece88e3c7ac02a569454a42ca8795cdc458a301f5cbc55eb99a902' 
  AND token = 'S5hEsfueLqmmtM2k3UMojj2lFimY41gJbU7KIm17IR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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