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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8434279a6945b08ec6bcbc4d1df04db1547a24f4a3a1d5d895beeeb7ff364efd' 
  AND token = 'D6UWFA3HG1XbqPLEKTRVvk7KM5NqIUBAxPzS7IZTX98=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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