SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d4772f626380ccaf79358cb0d2697546e2f2aa808f2b76fed0f490aacce51a0' 
  AND token = 'pETAIr8SyKgpGJRM32HCKcwOaChqWNKH8jkcvA3iRCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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