SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cb8719e1df501c39896ce17b442aac0a6ef7fe50f48db5769a622e85ca519ef' 
  AND token = 'U+pouHDa/d65LCaggeX8jaWbMvxGrDcI8uUAU+eVepA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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