SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5b44cba308fb5be2de902644bfa5eea98730fb865382df74269dacd35151f84' 
  AND token = 'tHFF5AgTRINg6GKAHgpdX2TdvdYXL8t97KKdmK1EghA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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