SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f49638119483218b5abc36194788ba8815955adc7412937f06d7467fc84856d' 
  AND token = '7Ex8ntETpr6LgR/Ds82YNALIisfEM2fii2LhJPPY3Ws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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