SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1e55dfb649fc913068f13228797acdf2978eb86c7c78e9c624200549479885cd' 
  AND token = 'D5iuJ6gUq9AJrlQm6R3XUVp0zGvGVuJN7XyJcghMMA0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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