SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d9d372d889003520e06f1326fcb305b8b37848753f0e0f84928f7ae843a91a2' 
  AND token = '5ZzXNF93BCYGEBuXfCcKnTYsXlut485wNQg+VzKpnc0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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