SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '242df68ed73ba9a8abc56708d81107064a973a6fcdaa868b210f966f86281329' 
  AND token = 'SrJSzGd93wLObCtndVijVXUMAd7CZtm1XvLyCjQPVwM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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