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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e14ce00d0ceb7c0ec521198a89f9ef38dd2e30a23f905814edaeddaf34e89383' 
  AND token = '6TD2gM3nCqwbfRypww3Q77nd7oS2saZIrYa8VCtcJ8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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