SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b92a7d0354a366fda91f8014ee63b8437792da0ad30182635fce9c0628159973' 
  AND token = 'vgMyGR4dnLFq8mP7ok1UVKJxLdFkAUF781GZiS5FzuI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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