SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4f4128436fe804d144ac0b9117525042df29f19e104169464c9fc6e7b4fad43' 
  AND token = '2pV5PaKnBDmKTHFjXD7bezXdXIN8C84jWZxRytQsKwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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