SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '249047703dd4bb6441958da4a53e4b49df797e1af20ed9d42846128ec5af3d01' 
  AND token = 'XmYWEEoO5s0zV/YcSeolFfH8lhbLOsg+7eejQgRvZrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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