SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf3b2b935b513a45d99dcb9ffbca608fc2af0771662edcfd049e165f84bf5c66' 
  AND token = 'xtMXhgPVlaT2NUNcysD6+qjO5VUKy2qBtGA9uhfzvKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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