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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bba1c309cacfd6b1c9fc3ac4b461802a3fa687ca194ab175da29a7b6801cb212' 
  AND token = '4xizwsnJDykpvKad0UgzTPdtSTsKN7f1IugDv0+EHzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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