SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '803400d824b30dd1990e9ab7f18a871bac8cc5f75223b97f85fc908051908852' 
  AND token = 'GpzOSFfQJglGnGdQz3zYugOuFl4YaCXE4/wXzKcEyso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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