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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bdef6a9411d0d5dc4c938471d0a53980e36b2e525af0783014a623b4ba4ab70' 
  AND token = '21ZM4y52Tz5kTAgYg7C0ZmiThI8Pl7E3GO0+p3r6rpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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