SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd027300554b3025f1db737a273e0840cf23d8b5fea39aff372afdf987b95e3b' 
  AND token = 'zY4c34zTZ9ymEjWe84bEDjz+32U9CG/fyXN9nWAXAMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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