SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99afe65b3774158f2ff1068224167587f25e2a97da708e24438a73c13ef5bc20' 
  AND token = 'kOgFlGQL1YtBx6/6aAgyudmFyuSLzwV3TEBVfK/nCpE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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