SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c83983685d53a6a333141e77bd6215cb0857c1a726fa2d192e8894af9fb686b4' 
  AND token = 'uQzs9zqum87vFHOF7m8dTKbWzY8gynJ/x1rncQrKWIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}