SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3f3c25b1da0b7d57f8b71d50474adac9785aa7ddbd12d13228ece6616add883' 
  AND token = 'I5eTKoCabvutySmbdkpbuuxrX4PnDG8mFMoMdy76FkQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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