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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fcf3ad8c044e2efef56ac6808d367d2a261c72577958396ffd45381f7dfe4bf4' 
  AND token = '5/GjGEQOFnfUMBbewsKB1tN4kGQPwrSi6/DRpYn786Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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