SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75cf8be591bf604eff034081853f1133314dd61915a804e1cceabe53b6be6d33' 
  AND token = 'Iq5tc60ad5hgM8m7RF5USIgnESRl22xu5CHbVIo3fH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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