SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa55f5608d5e12d67a2ad0209f9870bb141bd5edc112db576a9fee39600ead00' 
  AND token = '8zgObxuHbHBvlHoRpeff69zfEprC1SzXti1JiVLASZw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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