SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '52047d425ba2414b4820b8494fac1e474bc183aa9402cc778fa4eda96549af50' 
  AND token = 'Sl8EURqC8P/s6GgxUnDKUvH2CX63/2AEWFvaLZdxPZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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