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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e4b4aa27310eeed6c13209f598d6100ce701c4cd2b5745de59e8b9d75a715a4f' 
  AND token = 'U/Bhdx5tnFUs0V+LEWVo83J5CAwoPGiuFWW5M3BG7xo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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