SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '27279edf69492736125b25749511509a485f567a764f36c49326084f127d111b' 
  AND token = '2tYPlLj/i5AotZGLyT1ygGsGeqVj2agY1bndCiN7wSU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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