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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c4e6f929c7aec5d10d5fc29fb2bf0f51bc75f6d20c83832504a582484b47c2a2' 
  AND token = 'inRgVW5wcaKy6Wk6wkyd+Ir92WBL4Jtf5PHmYEkr8sM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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