SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14359b1d3ea00138d57ef9db60a30f42f8873425154828ac43bfaaeb04419423' 
  AND token = 'iFg2MG+AMTJGKiupa3xJg8eQLAxw9seFXEp+NFUOUk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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