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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'da0c8a9c75220df0a3d4735414483e5d42a70f94b561786498b915a81aa4feef' 
  AND token = 'm6/afUb3N9DWrFfoFygHoAxwgdV5VmIdscPxsT74RF0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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