SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f3b5063f628caa830d917fa55f57a9ec4a708a0f16efbbbefa1366088f75771' 
  AND token = 'bA1myBiRrEzoK/JeQa4PLqLLtOiLtjH8B31PEEeawqc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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