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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5cb8dbac524dc3f6615b7ca3d18fc97a8142cfcc53ff229a2c0c84bf594dcc0b' 
  AND token = 'g9bWpE8+CwEgs5qlzHSMcHKC/Y/whTWNSOgA0AJwjbo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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