SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77491f2e5af1799e5fcc32d7ae5f6ebd910cb2d765c8d2e0c9f5e33fa0c0c425' 
  AND token = 'mGadCHPY4vGd2fNrtqUBsk/uUmkGftazAQKbhbPnLkw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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