SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '688d618840d4ad60a194d1050930f64223329d66f15139b6476cc8a71b4af957' 
  AND token = 'sZRj6l1hjJ+OQjQeUN+XfWa9QMx0FV9zq3paXBzoUmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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