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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fc0aa43c64d473d7ae99c5df0e96306c31bb7fb9e3a5b89e770e0e0a38f9b668' 
  AND token = 'RkMjhfZ4Jf5gEG5uU2sTda7Va95oRfkrb11MckwN1dA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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