SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b783f661447f4150c6dfca93413a081ea0b0ef329d55b0c2bd450d3f0614628' 
  AND token = '5bQhDHCWdlGSDDoJPPHgCpUYEVUzbexgDOonvrZup3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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