SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29f5fe366054afa8391c0b24d8224d65fea98c2b6b7f926ac16933778f426c90' 
  AND token = '6fvgvGdVT9GZ459rGITqDGiOKFafZjd3+1kosDWMeO0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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