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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '31777c847153d00eb57ec43f85ea97ed83e81737a4883f8cb39de7d8e0dfcbbb' 
  AND token = 'BkoEqskkqYbpw9Tps917Cg7rP8+EZ5MyAtno+3onhEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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