SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78ecc426136e4666f12637b7bafd0d003324427275079e1b4c1437f915ee0b9b' 
  AND token = '0EaHW5V590AFmMVjzjDGSda2LI1E+/312TGIDJiztxI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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