SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '58ab9fcf429f6b5d17d0645adafcc92b2327be18e0e629340617aeb6dd379836' 
  AND token = 'L59sKmCX51+VvE1gPDT8yAE9yBhpuTv988/Kp3+rFHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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