SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9cd9eedce72130310a8f6fa9fe42a46a2363bc06fb8264199ff4d90e67961774' 
  AND token = 'tWTb4c5AhejPQqotf6UuwR9S5N2UDmBLFp4V1BJs0Wc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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