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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4fec65cdc3d5877092e330114bee4ff52f484390a4137bb211961ecc89d3ac0a' 
  AND token = '0/kWylN/qHE4RzRbuq8XysiTVWvJYnO5Lke2nlffA+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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