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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '31ab3540b23f5f6b9d2279813e3be4fe3d2e7559fa38f17419e82739ed486d71' 
  AND token = 'at/5Jb6/t8pSkPVtm0JOsTuXGvJE4SuLj6370jNb+GQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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