SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5377a514d3ba26ffb571107e3f7182d0e475c84fcad1b50fe6f6cb3f43af60b4' 
  AND token = 'yTAlRB+aJfu7ukpHCKNYuu88v+pa9HRfagKhh/X5Npo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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