SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b72c63166117c7d672595861a70b400a20a79b706a5814147ebab683b8570c10' 
  AND token = 'rWkNEvXXKoVmyAYQbndsD8E05PSgvfyzZ2aSVuXcBME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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