SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6a07b0643d83c9e406f20d31e0e795b358d9187f9c83d68dbf6e16efa1c9972' 
  AND token = '/SiZ/BINUvdmJUSCvMhmDvswUtEnUgFLdOINGoRaVfk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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