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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a7e9b6a6781641c345264df73f747e594e2302d5541b00b4ac936d7c8c9ee1e6' 
  AND token = 'TA9Dip+f2x3jDFKjrU+7HbFKac0lK74jT7FEvX8UaJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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