SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8dc94e8eddf0a53cb87cf5a025ad88dbecc4dde9da944ccd17719aefaceac83' 
  AND token = 'MaoUdYYtqXrxpyth+cotoPsUm1O+85qlo18vIQFLJ0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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