SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'd876917eae85be872519cfd690237e6a84a3234ca6ff8d760e4a2e55f7bd781a' 
  AND token = '+Wuyhvp4V2fpSbm09h0rCq9k/RAWgOw1RxVTIXsayB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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