SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b16e9c547f24371950232a5c8f7d52107d71d96108a53afb669caed2e47dd2bd' 
  AND token = 'sS/LSD8qdDLe3vvYaYYDgzO371QzPPbrJptBmjFx+H0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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