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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3f569d24a94a04aa7834f4a474ef2b4fbf23f5d5c7da027e5d0731fdcfed45cc' 
  AND token = 'uHBwA0kORtQHtgHNy1rDMMdErHMYc5+1eav3i08T+gA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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