SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51836bac3d95113ed635e60333c63f8a46da0d758bf38b191f05dc0def5d6421' 
  AND token = 'GVUz7uEuQ4b/7WMWP743A7mFGiz1/NZ9G0zq08O2iA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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