SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8aac2be3c7b1d23f9684025aea0102f0e51bf9b44243e76ecea68cd49e6970e2' 
  AND token = 'AITjgTFCc00T/cbjUkRPVyNOtZQl2MntHMFLBM1j14g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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