SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e50d36933247663c1383ce7d1eb93a53687098ab07a508bc00340e00c8eddf5' 
  AND token = 'F3YfdAOvHmFa/D6ITScVArSW6UGeqUdzdXiCpZEIxyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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