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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e25b74bf7b9d881a99c5cd2f1f6bbd47fd64ad880cd413b1ef6f82a3042a644e' 
  AND token = 'RM/miOeeH7Hb2p4dIYwzU5RVaeduZnYFNqOV3fEcleo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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