SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d87795909fe5980da410207c46161b44cc9d68b8f7646a65c3e5578536024bd' 
  AND token = 'Fs5txuXpKgL4UY6viz5dd+ACBfpvG9+vDTm6c3Pp4Es=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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