SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e8dbbff8a749dd0dbf7a6d3073131ec54b8dd4d050a880f80f2ebe361ceef85' 
  AND token = 'PLnK7RIqRHHaLtKP9tHyog0Dw0BSV85EoXR5ITzIgxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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