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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8dfcd1e0df6d304e31b3a3a03fadd50ad7c7cdca3f3665ff2d45ef0511cb261f' 
  AND token = 'hPiIQcMXv1InKKomVkhath/85j6fEgd0pYl54TH23LU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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