SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb5ebe7483cb50eb37d42001e5b0dc82c616bfd142dfb0a99cf268b1da42e555' 
  AND token = 'ucOZN0zf4rqXJwCsB6eJi0GvPewMTNqbtCQCuDFr9Y0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}