SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7957a9c9527f7b8de894d03ec3867b10451b838d2a175be399ac6e04741b0783' 
  AND token = 'Mi4lBcDS8YLZXSf8vtUcaV5RIEW+w/ji5fgKHkVQZ4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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