SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e45b278a852181ec650817df6760df97c690dbddde64caa1552d30e679903e50' 
  AND token = 'e7oeKSlBBq58x8jCuWfNZHXGxO1cfkX3icSqVchoLBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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