SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4e2eed3d3743af3c79aa0b33cd5cd36fe61f8d14648089c7eaf5a6a2af91817' 
  AND token = 'kQYqw2GlYCxWztVpyDXZIfdrSG90I3QsB+mNz60utdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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