SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '041889376835050b1602c4538621fb90894fdc9f7a6db3541494160713bf0a10' 
  AND token = '84ViuHt6Y+eNPgTPjmATWKrcv/wzCy/cVWPNo0Gp6Y0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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