SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fff3f9c6b9ae75fc2943f0c07d98a81c59cac4059edfd2333cb03875229cc99a' 
  AND token = 'Fv/LNBrRYEyuiHqyGLCZp7W7SaUTehzqlX6S+Sro0O4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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