SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b68a46598cd55e9573ae91001fbb1f63702648487cbcec71bfc5c9ed61a8680' 
  AND token = '9fg+aSQevAfnJbheukbD68ERH3WYjaIVoAU8rjfYgAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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