SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ddf86d72c6671e9907112beabf2aefd73bc23782c6a5e8cdfa90a6966c16dfe' 
  AND token = 'UUsjivRxcrscljO59aL3ThvxvjH5lzFcjy0Txr6b6i8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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