SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f64e4f931b14eac2595240cb98df5555decbf6b52f870a0c81b5db1072ed24d' 
  AND token = '2MyjwahRzr0bLsRCXqLbb0iDev5ezgU+FG4CR27PHas=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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