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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6c3694b82f9a116db13299f7c8361c8749de9faf51ba7430d8af0985ac62aa9' 
  AND token = 'PZkamlghRFQedMjtxzwLMzkGGHRDXXAH5V0rO09Un6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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