SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5166af2b6d6cc774aca973d3950c19e0936fd4cc8878be53fc8615e2b6afec5e' 
  AND token = 'GMX2qR7t65tNGlz08YDNPG8fJ4qiUGrzSXfNQzkVGLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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