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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3fde8adb3609a166629253057c3c49b7d12d35c2738a0b45eaf873e0a6bac361' 
  AND token = 'F3C2AjBClldIqfRQBQwuxMMkoE/oBvWd9p0WQz2+wcE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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