SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37fad3733deb10ad419d6b03e5447501911aec4f37050670270ab9f016842eb9' 
  AND token = '+TkEqUHzO38iUyoei356Q+tjr4WXUKBXuMtKjbSZfbI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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