SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f232fe5e0dcdcdd311a4b1692d6386c195886a25a463260518f5541ff4e618a2' 
  AND token = 'P8VJ9M4gXONZDTnAjtJZG7KSzwgRY160kinjI3FreGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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