SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '506965a7ac89d9b52fd6bc236e7244ff2d582642a6474e1e66802e63acfffc88' 
  AND token = 'cqjtmFJtzbTKaTwrbmJZkQEbJ751/I+QWeMLmy6JDL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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