SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b73edb5560ed5655543c811899f4cfd2f429bddecedf5944ea30532f8b686b1c' 
  AND token = 'mgyFcGzGRebrIDfIH3/nGnrEs4Rumz+/MIa83JrpBx0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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