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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e9e3265fc1c81ce629d83721c3391efc41496e1310bc331adb7fef8976cddb5c' 
  AND token = 'vEcN1PWBSg9NOYaVG95la0kD6fkASur84zG+vcnUzXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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