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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cbf50458de4c47a7953eec54ca9423cf4bf13bbac940e26c29c97917bbeb1393' 
  AND token = 'ydjltYyGJqZQE5d8+2LT3WNSyDtCWxumtqp9znbQP4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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