SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3d5ab91c8d639a5378703b650dd9bc54652fccaa94a201caaabea68f252a744' 
  AND token = 'YCJqZ8pzMyVJGW6rvctUlBJuIPfcG1W2/f8PpSyXVpM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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