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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd6c3c6a7b138a8a9773030615fce1c2694d2b09ab84cac6b1e1d872b4cbe18a' 
  AND token = 'iZiRu/84JB0eWdXlk+Yid+9n0YFLq+kco7nX6vJjjjs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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