SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83ae5449ca7514754dff77d26168033711bc795b75387e95c9f737b6d4e18835' 
  AND token = 'tvMO3sloFTmcxaNYQfxzwTidqqWgMxX3QXQwZue6PYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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