SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a120ea1d899511225eca703c83302df291156b227a5f2013a007a72cfb9173b' 
  AND token = 'MfV+VHNeYXAjCI8SIkBVAnOJDn033fkAMgEOQmWyszU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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