SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8538cbd0932b1863dc7ca4c90619afcfd20a9aa5f105ece905c47ae8c442bcc4' 
  AND token = 'pO2KFNxCFSYhPpS1qrHUQ9ls/UPDWbfgM+I/+hn4P5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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