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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2596edf76485ad4f43748d1c55fa687bf669bdf3e88e9b29d3003425a36d2568' 
  AND token = 'k5BiGhYj5Mg1p4300lhNLDEtSRPEOv3U5wz/sdMRay8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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