SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '262e2861a583874ad7bc478b2135abb52cd44c7f09450a7c1ebd40cdbe427412' 
  AND token = 'bua1vxrMI4EhDz48845yCGrmthJjiqxlAYVvic5EDrE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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