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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '81ad7e19bbdaa75930a5ca9d028359e5f2c5c9266d9443e8e7063d30fd18f7ba' 
  AND token = 'dikV34DFN3npkH2SoH3aU1p7qt4dqdLi/vkLgOOCCBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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