SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83c78e54722bdbd809d7143bba4f3ce6d6ba064deef3d2f29543cae61ebd973d' 
  AND token = '+Ramx9XFU0XrGnGqwlfYN51Y2gSxzAjeLutFpUfgDeE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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