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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3b2d09e00cfac70bc546ab8a28e31b5da6c0bbe88acc4ba5b092bc29ade1e496' 
  AND token = 'Lk27ft2byfkgmmMAdDO5mtg7p6mvgZ8CKfklhMTZfoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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