SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ec229add16221954871568406081a2e37e842e552eaa634ded8976744f65246' 
  AND token = 'Pyyzt2dvZcfvXaQfx3l8ODeJb8SGF3YaWxtIDzHgbgM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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