SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3fa8a640a374fcd14722d1b5ced7e973fff9517359d58d629c4a88f2f200d41' 
  AND token = 'bSR3lguonlamDrlqANVY4hviyBp2AIeZ7lfYhOVdZRw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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