SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71989f3d54bd1608656c2ff5f6bc6df86e83046a1085f39f0a3974b024010e92' 
  AND token = 'x2lIlF18AJKu3QJwGLh+nQVVVSY/PVTL0a91lODYQUM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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