SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b6cb835d0c3db794c3e0ed758e49e8f0358b5983958b325f64ce1d7289426c8c' 
  AND token = '5DR08MSkNxjfsymOJoKw+zn6I2+F007NkF3rZZdijNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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