SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2694fa7951437c8a6785a0ad0f9f93fe75cc75f511cdfb91754a33ce922ba842' 
  AND token = 'bywG4ZxpoPMjNRRA+Wfu4fA5BPYYdxERoVQNPPXi3+0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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