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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a7e38e2dffccadbc6b9cba7aa6a718b0bbbedf21fb7c47b5372882762a193184' 
  AND token = 'x1tGxcJ34s2Vinr2BOWZ8dQbSB//GSed5+HMp1AMync=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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