SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6643639df7fa3117502db34caab720c7457556d3f46c69575a1c546108a1225b' 
  AND token = 'PEWzxfgtlVohxMI2aOsE0SRRJEJZ+d1Gq5r+71e/NAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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